My hike has barely started, and already I’m sweating profusely. I’m breathing heavily. My glasses are fogging up. My backpack weighs 48 pounds but seems heavier. A mosquito attacks me and I immediately regret my decision not to bring bug spray. When I take out my binoculars to look at some barn swallows, my friend Josh, a nonbirder, teases me, asking whether there are any “yellow-throated South African quarry fowl” in the area. Meanwhile, he cracks jokes about how we’re almost out of water and that he may have to drink my blood.

That early June morning, Josh and I had taken the Metro-North Railroad from Grand Central Station in Manhattan to Pawling, New York, just a few miles from the Connecticut border. “Be safe, have a great trip,” the conductor told us as we jumped off the back of the train directly onto the Appalachian Trail, a 2,178-mile footpath that runs up and down mountainous terrain, from Georgia to Maine. My plan is to walk the trail’s northernmost 741 miles, a journey that should last two months. Josh is joining me for the first five days, my wife will meet me for three days in Vermont, and my brother will accompany me for the final nine days. Otherwise, I’ll be alone, with no one to help me if I get lost or sprain an ankle.

Keeping my pack light is key, but that’s hard because I’m carrying most of what I’ll need for two months. I have a tent, sleeping bag, sleeping pad, water, food, clothes, a pack cover, a small camping stove, maps, rope, binoculars, a water filter, a first-aid kit, and a bear-resistant Kevlar sack. Everything is made of synthetic material (cotton doesn’t dry fast enough and is too malodorous). I leave my watch and cell phone at home. My only possessions that require batteries are a headlamp and a satellite emergency notification device. My camera doesn’t even make the cut. Still, I’m lugging more weight than most hikers on the path.

Josh and I spend our first day, which is sunny and warm, hiking through meadows filled with wildflowers and sections of young deciduous forest. Sometimes we talk amiably, while other times we walk silently. Sometime around 6 p.m., after 9.6 miles, we pitch our tent next to one of the three-sided log shelters that appear periodically along the trail, and go for a dip in the nearby Ten Mile River. The waist-high water is clear and soothes our sore muscles. Back at the campsite, we steer clear of a hiker who’s carrying a machete, and chat instead with a guy from North Carolina whose trail name is Insane. On the trail, for some reason, real names are virtually never used. In a thick southern drawl, Insane recommends that our trail names be Mudflap and Riffraff. From the look on his face, it’s obvious what Josh thinks of Riffraff, and he says I might be settling by even considering Mudflap. We mull this over while cooking dehydrated corn-potato soup and watching the fireflies flash in the twilight.

The next morning, I wake up to a wood thrush and veery chorus. “Hey, Mudflap, how’d you sleep?” Insane asks. I decide to stick with his suggestion. It makes me sound like someone who answers everything with a grunt. Josh, meanwhile, chooses Nutella Knee-Highs as his trail name. We break camp, walk along the river for a while, and climb through a grove of pine trees. Mountain laurel, its pink and white flowers in full bloom, lines much of the way. Right after lunch, we meet “Silver Fox,” our first through-hiker. Unlike us section hikers, Silver Fox has walked all the way from the start of the trail at Springer Mountain, Georgia. Despite being almost twice our age, he is moving extremely fast. Other through-hikers similarly blow past us, moving about twice our speed. “We’re either fat, or they’re on steroids,” Josh says.

We’re burning between 4,000 and 6,000 calories a day, so it’s hard to keep our energy up. I get on a regular regimen of oatmeal or Pop-Tarts for breakfast; dried fruit, carrots, chocolate, beef jerky, nuts, peanut butter, crackers, or the biblical backpacker food matzo for lunch; and ramen, couscous, macaroni and cheese, or freeze-dried meals for dinner. This cuisine tastes mediocre, but offers a lot of calories for the weight and doesn’t go bad easily. The trail never strays far from civilization, so it’s possible to re-supply in grocery stores every few days, even dine in a restaurant once in a while. But because I’m constantly hungry and craving strange foods, I spend an extraordinary amount of time thinking about the things I would do to a chunk of sharp cheddar. Josh hungers for a hamburger on a toasted bun buttered beforehand—an unlikely admission from one of the healthiest eaters I know. I catch him ogling candy bar wrappers in a dumpster while he chugs a Powerade. “Brominated vegetable oil never tasted so good,” Josh says, looking at the ingredients label.

On Day 5, Josh and I part ways. His timing is perfect, because for the next four days I trudge through rain. As I cross from Connecticut into Massachusetts, nearly everything in my pack is wet. I also fall on slippery rocks and crack my walking stick in two, scraping my hand, elbow, and side. My mood brightens in Beartown State Forest, however, where I see more than a dozen red efts, two beavers uprooting marsh plants outside their lodge, and a great blue heron spear a large fish. The following night, I stay in a cabin right on the shore of totally undeveloped Upper Goose Pond. About 10 other long-distance hikers are there, and I listen to them exchange trail gossip and talk about such pertinent matters as the most effective ways to urinate at night without getting up. In the morning I wait for them to leave, go down to the pond, strip off all my clothes, and swim in the pristine water. As I dry off, a kayaker comes around the bend. Luckily, he isn’t perturbed by my nudity. “Beautiful day,” he says. I have to agree.

By Day 13 I climb up out of Massachusetts and into Vermont’s Green Mountain National Forest, where the terrain is slightly steeper and wilder. There are higher mountains in Vermont than in Connecticut or Massachusetts. It also seems much more remote because the trail is now in a national forest. My heels are sore and blistered and ready for a reprieve. I spend the next three days in a hotel with my wife. I leave her with a heavy heart and my extra tent stakes, which I don’t need. A lighter load helps me to walk a little faster, covering 21.3 miles one day. The trail in Vermont continues north and then veers east toward New Hampshire. On my last full day in the state I see a tree fall in the forest, slosh through mud up to my ankles, gorge on wild raspberries, and pass through woods filled with birch trees and stone walls. I jump from a bridge into a river and camp in the backyard of a man who entertains me and two other hikers with tales of his small-time mob ties, his 1915 Model-T, and his near-death experience in a snowstorm on the Pacific Crest Trail.

Two days later, nearly halfway through my adventure, I stop to watch a bright-blue indigo bunting feed its chicks in the middle of a field filled with black-eyed Susans and daisies, signs that July is here. Ahead of me is a climb up western New Hampshire’s 2,290-foot Moose Mountain. By now, on Day 27, my legs are much stronger and I power my way up all but the tallest peaks without a break. After a strenuous 75 minutes, I reach the top and sit down for lunch. As usual, I attract a swarm of black flies looking for a meal. Suddenly some dragonflies come to the rescue, emerging from the bushes to engage in aerial warfare with the biting bloodsuckers. I cackle with delight as the dragonflies bring down one black fly after another. I quietly beg them to follow me the rest of the way. It would have been a beautiful symbiotic relationship, but instead they zoom out of sight.

I enter New Hampshire’s White Mountains National Forest on July 16 and am greeted just below treeline by spruce grouse, boreal chickadees, and other bird species not found farther south or at lower elevations. It takes me a few more days to reach 6,288-foot Mount Washington, the tallest peak in New England. When I arrive, the top is completely fogged in. Tourists who had driven up the auto road surround me, snapping pictures of everything in sight despite the nonexistent field of vision. Giving in to temptation, I eat at the overpriced snack bar. I have fewer problems resisting a “This Car Climbed Mount Washington” bumper sticker at the gift shop. Instead, I get back on the trail, where I feel more at home.

On the descent, the fog clears, revealing beautiful vistas in every direction. Practically the only living things at this elevation are lichen, grasses, and a few alpine flowers, giving it the feeling of another planet. Meanwhile, the wind blows strongly—another hiker later told me that it was gusting up to 70 mph on nearby Mount Madison. In the steady wind, I veer to the right like an unaligned car. Snot flys out of my nose before I can stop it. Every now and then I see a raven calmly and gracefully riding the air currents.

Hiking in the White Mountains is strenuous, but southern Maine will prove even more rugged.

Maine’s Lone Mountain, at 3,280 feet above sea level, is high enough that balsam fir and spruce trees have almost completely replaced the maples, beeches, birches, white pines, and hemlocks found at lower elevations. The summit is sparsely wooded, but the forest becomes denser as I make my way northeast toward nearby Spaulding Mountain. Without warning, I hear a crack in the undergrowth, and I look up to see a black bear a few dozen yards off the trail. We make eye contact for an instant before it turns and sprints away. It’s funny to see a bear running so fast in the other direction when the squirrels and mice generally hold their ground. But avoiding humans—even skinny ones like me—is definitely the best thing for its well-being in an area popular with hunters.

Soon after I leave Lone Mountain, the terrain mercifully flattens out a bit. The last nine days of the trek loom before me. Evan, my brother, meets me for the trip’s final leg on August 7. He is joining me for the so-called 100-Mile Wilderness, which, while not a wilderness in the legislative sense, is the longest section of the trail without any paved roads. “I didn’t want to say anything, but your appearance scared me,” Evan tells me while laughing at my odor and ratty beard. After struggling the first two days his legs steady and his pace improves. The weather, however, deteriorates. We walk through mist, drizzle, showers, off-and-on-again rain, steady rain, downpours, and thunderstorms. Both of us fall numerous times, and I can hear Evan murmuring prayers to the sun god Ra.

One especially wet night, we camp on a patch of grass next to a fast-moving stream. Many hikers prefer sleeping in the three-sided log shelters that line the trail, but they’re often littered with trash and infested with aggressive mice and mosquitoes. I usually set up my tent instead, but I have also spent one night in the recreation room of a church, another in the laundry room of a Dartmouth College co-ed fraternity, and a third “cowboy camping” under the stars. The freedom of not knowing where I am going to sleep is one of my favorite parts of trail living, but I also enjoy the sense of community among hikers, avoiding modern technology, getting out of my normal routine, and birdwatching on a daily basis.

A couple of nice days, complete with birdsong, reenergize us. At the base of 5,268-foot Mount Katahdin—which towers over everything else around—we’re in good spirits. This mountain marks the endpoint for both our hike and the Appalachian Trail. It has taken me 59 days to get here. The trail up the mountain starts gradually but steepens fast. Once above treeline, we use our hands to propel us forward over a series of huge boulders. As we get higher, the fog and rain blow in. The visibility is so poor I can barely make out Evan hiking 20 yards behind me. Finally we reach the summit, populated, at the moment at least, by only dark-eyed juncos. It’s cold, so we don’t stay long. Going down proves to be as slow-going as going up. We have already walked 20 miles since morning, and I can tell Evan is functioning purely on willpower. He keeps saying things like: “My body hates me” and “My legs are saying ‘no, no, nooooooo.’ ” By the time we get back to the campsite, we are both exhausted and can barely walk. Appropriately enough, it rains our last night in the tent. Nonetheless, we both have bittersweet feelings about leaving these woods, where the lack of modern conveniences and the constant, sweet-smelling nature has given us great delight.